The revelation that the NSA monitors just about every means of communication is scary, but it also ignited a strong interest in security from individuals and business professionals. Confide (free) aims to be your go-to Android app for sending secure messages, and bolsters its slick offering with the ability to send attachments. Though Confide won't give you a threaded, instant-message experience, it's a good tool for quickly and easily confiding in people you trust.

On iOS, screenshots are the Achilles heel of secure messengers, and Confide is specifically designed to prevent recipients from taking screenshots of messages. One of the freedoms enjoyed by Android developers, but not found on iOS, is the ability to simply block users from taking screenshots. Confide takes great advantage of this in its clever secure messaging service.

Swipe to ReadOnce you've gone through the painless setup process, you're ready to start sending secret messages with Confide. I tested the app on my Nexus 5. Composing a message is no problem; just select one or more Confide users as recipients and start typing. You can also send messages to the email address of people not using Confide, though they'll have to create an account to read them.

Reading messages in Confide is a unique experience. The text of an unread message appears as a series of orange rectangles, sort of like a redacted government document. To read the message, you drag your thumb down the screen, revealing the corresponding lines of text. The blocks covering text you've already swiped over turn grey, and when you close the message the text is shattered—visually signaling that the message has been deleted.

When I first reviewed Confide, you could only read messages word-by-word instead of line-by-line. While the current version is easier for a shoulder-surfing spy to see, it's also easier to read. It strikes the right balance between security and ease of use, and feels less gimmicky. The latest update fully embraces Google's Material Design, giving the slick app and even more appealing appearance. That's rare for a security app.

On the iPhone, swipe-to-read was meant to prevent recipients from taking screenshots of messages. This simply isn't a problem on Android since the OS can block screenshots for certain apps, such as Confide. If a treacherous iPhone user takes a screenshot of your message, the message closes immediately and you'll receive an alert on your phone. An untrustworthy Android user who attempts to screenshot your message will fail, so no warning is sent.

Of course, a determined snoop could simply whip out another phone and take a photo of the message as it's revealed on the screen.

Security SituationThe Confide developers explained that their system uses end-to-end encryption, in which messages are secured with AES-128 bit encryption on the sender's device and decrypted on the recipient's device. Messages are secured in transit with HTTPS. The encryption keys are also stored on users' devices, meaning that investigators would only get unreadable junk if they compelled Confide with a court order to hand over user data.

The service is built on trust so you can send and receive messages only from people you've added via their email or phone number. I was a bit nervous when I saw the option to connect to Facebook and grant Confide access to my address book. Many apps use this to help you find other users on the service, but it's also an opportunity to grab a bunch of personal data from users. Thankfully, Confide said that it hashes your address book and finds other users by comparing those hashes—meaning that Confide can't examine your friends' contact info. The developer says that it does not store Facebook or contact data.

Confide's developers also confirmed that read messages are immediately deleted from your device and their servers. Unread messages have a 30-day lifespan on Confide's servers as well. It seems developers have learned from Snapchat's mistakes.

You can also use the same Confide account across multiple devices. Ideally, messages should be destroyed immediately upon reading. But I noticed that multiple devices sometimes took a few seconds to update and remove messages read on other devices from your inbox.

Sending Secrets A recent update to Confide now gives users the ability to send attachments along with messages. You can select to either take a picture, or attach a file from your phone or a cloud storage service like Google Drive, Box, or Dropbox. Currently, Confide sets no limit on how large a file you can attach, but the company explained that some devices may not have enough memory to send huge attachments because the app pre-processes documents locally. Your mileage, it seems, may vary.

As a sender, you'll see a thumbnail preview of the attachment. But the recipient sees a large, but blurry, image. Tapping and holding a finger over the image clears an inch-wide band of the image. Like revealing only a line of text at a time, this gives the recipient a pretty clear impression of the attachment without ever exposing it in its entirety. That said, I was reminded of the titillating and tacky Obscure, which let recipients see only a piece of a picture until the sender decided to release the rest of it. Secure file sharing service Dstrux also uses this tactic in its desktop offering.

Unfortunately, Android users can only send images and PDFs through Confide. The developers tell me that this is due to limitations in Android, a phrase I've not often heard about the platform. iPhone users, on the other hand, can attach Word, Excel, and PowerPoint documents in addition to images and PDFs. Android users can, however, receive Office documents sent from iPhone users.

Note that attachments in Confide cannot be opened in their original format. That means that you won't be able to make edits to that Word doc you received through the app. If you're looking for a secure way to share documents, consider Editors' Choice CertainSafe.

Confide With ConfidenceConfide had always positioned itself as a smart and sleek way to send messages, and targeted professionals looking for a means to quietly share information. The addition of attachments and streamlined reading will certainly appeal to the business-minded, though the limitations on Android are disappointing.

Editors' Choice Wickr offers a similar means to send private messages, but gives its messages a pre-set lifespan before deletion. Cryptocat isn't nearly as polished as Confide, but allows for anonymous, encrypted messaging. TextSecure also offers encrypted messaging, and supplies RedPhone for encrypted VoIP calls. Chose the service that fits your needs, but keep your secret messages secure.

Max Eddy is a Junior Software Analyst investigating the latest and greatest apps for Android. Paranoid by nature, he's also keeping an eye on emerging threats and countermeasures at SecurityWatch with Neil Rubenking and Fahmida...

Automatic Renewal Program: Your subscription will continue without interruption for as long as you wish, unless
you instruct us otherwise. Your subscription will automatically renew at the end of the term unless you authorize
cancellation. Each year, you'll receive a notice and you authorize that your credit/debit card will be charged the
annual subscription rate(s). You may cancel at any time during your subscription and receive a full refund on all
unsent issues. If your credit/debit card or other billing method can not be charged, we will bill you directly instead. Contact Customer Service